There are certain stones and other minerals which, owing to their possession of numerous microscopically fine cavities, of a globular or tubular shape, have the appearance of "rays" or "stars," and these are called "asteriated." Several of such stones have been discussed already in the last chapter, and in addition to these star-like rays, some of the stones have, running through their substance, one or more streaks, perhaps of asbestos or calcite, some being perfectly clear, whilst others are opalescent. When these streaks pass across the star-like radiations they give the stone the appearance of an eye, the rays forming the iris, the clear, opalescent, or black streak closely resembling the slit in a cat's eye, and when these stones are cut _en cabochon_, that is, dome-shaped (see Chapter XI. on "Cutting"), there is nothing to deflect the light beams back and forth from facet to facet, as in a diamond, so that the light, acting directly on these radiations or masses of globular cavities and on the streak, causes the former to glow like living fire, and the streak appears to vibrate, palpitate, expand, and contract, exactly like the slit in the eye of a cat. There are a considerable number of superstitions in connection with these cat's-eye stones, many people regarding them as mascots, or with disfavour, according to their colour. When possessing the favourite hue or "fire" of the wearer, such as the fire of the opal for those born in October, of the ruby for those born in July, etc., these stones are considered to bring nothing but good luck; to ward off accident, danger, and sudden death; to be a charm against being bitten by animals, and to be a protection from poison, the "evil eye," etc. They figured largely, along with other valuable jewels, in the worship of the ancient Egyptians, and have been found in some of the tombs in Egypt. They also appeared on the "systrum," which was a sacred instrument used by the ancient Egyptians in the performance of their religious rites, particularly in their sacrifices to the goddess Isis. This, therefore, may be considered one of their sacred stones, whilst there is some analogy between the cat's-eye stones and the sacred cat of the Egyptians which recurs so often in their hieroglyphics; it is well known that our domestic cat is not descended from the wild cat, but from the celebrated cat of Egypt, where history records its being "domesticated" at least thirteen centuries B.C. From there it was taken throughout Europe, where it appeared at least a century B.C., and was kept as a pet in the homes of the wealthy, though certain writers, speaking of the "mouse-hunters" of the old Romans and Greeks, state that these creatures were not the Egyptian cat, but a carniverous, long-bodied animal, after the shape of a weasel, called "marten," of the species the "beech" or "common" marten (_mustela foina_), found also in Britain to-day. It is also interesting